For many devices removing heat is essential in order to keep the device operating effectively. Often, to aid in removal of heat, a heat sink is coupled to the device. The heat sink is generally a metal component with a flat base on one side and a number of fins on the other. The flat base is coupled to the device and the fins extend out from the base. The fins increase the surface area available for heat dissipation to the surrounding environment. Often, however, heat from the electronic device does not propagate evenly from the heat generating device to all areas of the heat sink. This results in localized “hot spots” near where the heat is coupled into the heat sink. Because the heat does not adequately spread from the hot spot, some areas on the heat sink may be dissipating heat only minimally. Thus, the heat sink is not cooling up to its potential, because the heat is being dissipated from only a portion of the surface area on the heat sink.
To solve this problem, some devices use a heat spreader to aid in spreading the heat throughout the heat sink. Heat spreaders are structures that have a higher thermal conductivity than their surrounding structure. The heat spreaders are generally positioned between a heat generating device and a heat dissipating member of the heat sink, and are oriented such that heat entering the heat spreader travels lateral to the heat dissipating member. Thus, as heat enters the heat spreader, the heat is allowed to easily propagate across (lateral to the surface of) the heat dissipating member.
To effectively spread heat across a heat dissipating member, many heat spreaders are made of materials having a high thermal conductivity in one direction or plane. The high thermally conducting plane is generally oriented parallel with the heat dissipating surface, such that the heat can propagate easily lateral to the heat dissipating surface. The materials used to obtain a high planar thermal conductivity, however, often have a very low thermal conductivity in a direction normal to that plane. Thus, although the heat spreader effectively spreads heat laterally, the heat spreader does not allow good heat conduction between the adjacent heat dissipating member and the heat spreader. Vias, therefore, are generally included to aid in transferring heat between the heat spreader and the heat dissipating member. Conventional vias are metallic projections from the heat dissipating surface or from an opposing surface which extend through the heat spreader and contact the heat dissipating surface. These vias are thermally coupled to the heat spreader in the high thermal conductivity plane. Thus, heat easily propagates to the via from the heat spreader. Once the heat enters the vias, the heat can propagate up through the vias and into the rest of the heat dissipating member.
Manufacturing heat sinks having vias and heat spreaders such at those discussed above, however, often requires expensive processes which add to the cost of the heat sink. For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an apparatus and method for cost effectively transferring heat from a heat spreader.